ppp between two machines over serail without a modem

Question

Can't delete this question. It was moved to another forum.

I'm trying to setup a PPP connection between two Linux machines over a serial line. I followed these instructions but it didn't work. The two machines are Fedora 28 Linux on an Intel(R) Core(TM) i7-7600U CPU @ 2.80GHz and a custom built board with Linux 4.14.0-xilinx-v2018.2 on an ARMv7 A.

Here are the commands and the output I got on a Fedora machine:

$ sudo pppd -detach debug passive lock xonxoff 192.168.10.100:192.168.10.1 /dev/ttyUSB0 9600
[sudo] password for user:
using channel 3
Using interface ppp0
Connect: ppp0 <--> /dev/ttyUSB0
sent [LCP ConfReq id=0x1 <asyncmap 0xa0000> <magic 0x888f0bcb> <pcomp> <accomp>]
sent [LCP ConfReq id=0x1 <asyncmap 0xa0000> <magic 0x888f0bcb> <pcomp> <accomp>]
sent [LCP ConfReq id=0x1 <asyncmap 0xa0000> <magic 0x888f0bcb> <pcomp> <accomp>]
sent [LCP ConfReq id=0x1 <asyncmap 0xa0000> <magic 0x888f0bcb> <pcomp> <accomp>]
sent [LCP ConfReq id=0x1 <asyncmap 0xa0000> <magic 0x888f0bcb> <pcomp> <accomp>]
sent [LCP ConfReq id=0x1 <asyncmap 0xa0000> <magic 0x888f0bcb> <pcomp> <accomp>]
sent [LCP ConfReq id=0x1 <asyncmap 0xa0000> <magic 0x888f0bcb> <pcomp> <accomp>]
sent [LCP ConfReq id=0x1 <asyncmap 0xa0000> <magic 0x888f0bcb> <pcomp> <accomp>]
sent [LCP ConfReq id=0x1 <asyncmap 0xa0000> <magic 0x888f0bcb> <pcomp> <accomp>]
sent [LCP ConfReq id=0x1 <asyncmap 0xa0000> <magic 0x888f0bcb> <pcomp> <accomp>]
LCP: timeout sending Config-Requests

And here are the commands and output I got Linux 4.14.0-xilinx-v2018.2

root@cpe-08:/data# pppd -detach debug passive lock xonxoff 192.168.10.1:192.168.10.100 /dev/ttyS0 9
600

Yep, you saw it correctly, there was no other output Linux4.14.0-xilinx-v2018.2.

I was expecting to see ppp0 interface on both machines but didn't see any of them.

Here is the output of ifconfig on Fedora 28 after running pppd command

$ ifconfig
enp0s20f0u2u2: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 172.24.176.116  netmask 255.255.255.0  broadcast 172.24.176.255
        inet6 fe80::63fd:53b6:8b94:1abf  prefixlen 64  scopeid 0x20<link>
        ether 00:0e:c6:a5:94:88  txqueuelen 1000  (Ethernet)
        RX packets 5016  bytes 457454 (446.7 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 1368  bytes 141981 (138.6 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

enp0s31f6: flags=4099<UP,BROADCAST,MULTICAST>  mtu 1500
        ether 54:e1:ad:8c:32:a5  txqueuelen 1000  (Ethernet)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 0  bytes 0 (0.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
        device interrupt 16  memory 0xec200000-ec220000

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 1000  (Local Loopback)
        RX packets 184264  bytes 109696260 (104.6 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 184264  bytes 109696260 (104.6 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

virbr0: flags=4099<UP,BROADCAST,MULTICAST>  mtu 1500
        inet 192.168.122.1  netmask 255.255.255.0  broadcast 192.168.122.255
        ether 52:54:00:62:c0:6c  txqueuelen 1000  (Ethernet)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 0  bytes 0 (0.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

wlp58s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 100.96.37.134  netmask 255.255.255.192  broadcast 100.96.37.191
        inet6 fe80::3728:7f03:ba95:5757  prefixlen 64  scopeid 0x20<link>
        inet6 2620:10d:c0be:2226:7261:932:1670:38bb  prefixlen 64  scopeid 0x0<global>
        ether f8:34:41:af:1a:0e  txqueuelen 1000  (Ethernet)
        RX packets 13305344  bytes 16391874252 (15.2 GiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 5691206  bytes 1228184162 (1.1 GiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

And here is the output from ifconfig on a Linux 4.14.0-xilinx-v2018.2 after running a pppd command

# ifconfig
eth0      Link encap:Ethernet  HWaddr 00:04:35:00:01:08
          inet addr:172.24.176.208  Bcast:172.24.176.255  Mask:255.255.255.0
          inet6 addr: fe80::204:35ff:fe00:108/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:2515 errors:0 dropped:0 overruns:0 frame:0
          TX packets:753 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:221227 (216.0 KiB)  TX bytes:93698 (91.5 KiB)
          Interrupt:27 Base address:0xb000

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:36160 errors:0 dropped:0 overruns:0 frame:0
          TX packets:36160 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:1516794 (1.4 MiB)  TX bytes:1516794 (1.4 MiB)

I know that Linux 4.14.0-xilinx-v2018.2 was compiled to include ppp support. I would have included an excerpt from a '.config' but it is not provided with the build. The reason I know that ppp support is in the kernel is because I asked our build guy and he said he included it. I would appreciate any help on this.

score 0 · Accepted Answer · answered Sep 26 '18 at 21:36

0

After messing around for sometime I managed to get it working. Here is the command for Fedora machine

sudo 0pppd -detach local debug noauth passive lock 192.168.10.100:192.168.10.1 /dev/ttyUSB0 9600

And here is the command for a Linux 4.14.0-xilinx-v2018.2 machine

pppd -detach persist debug local noauth passive lock 192.168.10.1:192.168.10.100 /dev/ttyS0 9600

I've been struggling with the problem for the past 2 months. Not sure why this question was initially downgraded. I imagine there are other people who had the same issue.

answered Sep 26 '18 at 21:36

flashburn

4,180
7
54
109

It was downvoted and marked for deletion because Linux operating system questions and networking are off topic here. Stack Overflow is for programming questions. You should delete this and ask on unix.stackexchange.com or serverfault.com instead. – Rob Sep 27 '18 at 00:25
@Rob Just out of curiosity, why there is a `linux` tag then? It also would be nice to know when the question was downgraded why it was downgraded. It is not always clear from the instructions on what kind of questions I can ask on this site. – flashburn Sep 27 '18 at 01:56
https://stackoverflow.com/help/on-topic and https://stackoverflow.com/help/asking Also, I don't know if you can see the "close" count or if you get some kind of notification of such things. – Rob Sep 27 '18 at 03:10
@Rob I don't have enough reputation to move the question to unix.stackexchange.com. I know it can be done. You seem to have enough reputation? I think the question is useful and shouln't be deleted. – flashburn Sep 27 '18 at 17:08
You can't move it but you can delete it and ask over there. – Rob Sep 27 '18 at 19:01
@Rob It looks like is is possible. Have you tried https://meta.stackexchange.com/questions/2683/move-questions-between-stack-exchange-sites? I'm not aware of all the details, but looks like for people with 3000 rep it is possible – flashburn Sep 28 '18 at 00:57

ppp between two machines over serail without a modem

1 Answers1